Most likely clamd is not running at all, or you are running Qmail-Scanner and clamd under a different uid. If you are running Qmail-Scanner as qscand (default setting) you could put User qscand inside your clamd.conf file and restart clamd. Remember to check that qscand can create clamd.ctl (usually located at /var/run/clamav/clamd.ctl). The same applies to the log file. The suggested setup is: put User qscand and AllowSupplementaryGroups in clamd.conf, then add user qscand to group clamav and make the socket dir and the log dir group writable by clamav.